Process of isomerization in the presence of a double fluoride catalyst



Patented Nov. 29, 1949,

utters PROCESS or rsomialzh'non IN THE PRES- ENCE or A ooonnar'monrm-z CATALYST Herbert J. Passino, Englewood, N. J assignor to The oss c fli ny, Jersey City, N. J a corporation of No Drawing.

Orig'inil application January 8,

1943, Serial No. 471,733. Divided and this application August 2i, 1!, Serial No. 45,567

1': Claims. (circa-483.5)

This invention relates to improvements in the activationof hydrocarbons in catalytic hydrocarbon conversion processes. More particularly, the

invention relates to improvements in catalytic condensation reactions of hydrocarbons, such as polymerization of olefln hydrocarbons and the alkylation of iso-paraflin hydrocarbons and cyclic hydrocarbons, such as aromatic hydrocarbons, by

means of olefin hydrocarbons, and to improvements in catalytic isomerization of hydrocarbons, such as aliphatic hydrocarbons and poly-alkybated cyclic hydrocarbons. This application is a division of my prior and copending application Serial No. 471,777 filed January 8, 1943, now

are effected in the presence of catalytic material comprising a compound of hydrogen fluoride and a fluoride selected from the group consisting of alkali metal fluorides, alkaline earth metal fluorides and ammonium fluoride. Such materials, which may comprise one or ore mols of hydrogen fluoride in combination with one or more molsof the other fluorides, are referred to her'einafter as compounds of the fluorides, double fluorides, or hydrofluorides of the metals or ammonium. The hydrofluorides of ammonium and the alkali metals, such as potassium and sodium, are particularly suitable for the purposes of this invention, but the use of the hydrofluorides of the alkaline earth metals, including calcium, strontium and barium, is also within the scope of the invention.

The various hydrofluorides may preferably be prepared by mixing the hydrogen fluoride in a liquid condition with a suitable amount of the metal, fluoride or ammonium fluoride. The amount of the metal fluorides or ammonium fluoride, which is added to the hydrogen fluoride,

hydrogen fluoride to form a solid derivative which has a melting point of 150 F. If it is desired to produce a hydrofluoride having a smaller proportion of hydrogen fluoride, such as potassium dihydrofluorida'two mols of hydrogen fluoridef and one mol of potassium fluoride are mixed to produce a solid derivative which has a somewhat higher melting point.

- temperature.

fluoride or ammonium fluoride in mol ratios other than'those expressed by whole numbers result in the production of a mixture of hydrofluorides having different mol ratios. Even when mixing the hydrogen fluoride and metal or ammoniurn fluoride in exact mol ratios the result may be amixture of hydrofluorides of different mol ratios if uniform distribution is not maintained during the mixing operation. This does not detract materially from the value of the catalyst, however, since the difference in catalyt- 10' activity of the hydrofluorides having reasonably similar ratios of hydrogen fluoride to the metal or ammonium fluoride is rather slight.

The melting point, or melting points, of the 'hydrofluorides increases generally with decreasing ratios of hydrogen fluoride to the metal or ammonium fluoride. If it is desired to maintain the catalyst in the solid form while operating at a relatively high temperature, the proportion of the hydrogenv fluoride and metal or ammonium fluoride may be controlled to produce a hydrofliioride, or mixture of hydrofluorides, melting only at temperatures above the proposed reaction The melting points of the hydrofluorides, in relation to the reaction temperature, may influence the selection of the particular hydrofluoride to be employed. The sodium hydrofluorides in general have higher melting points than the corresponding potassium hydrofluorides and the hydrofluorides of the alkaline earth metals have still higher melting points. On the otherhand, ammonium hydrofluorides melt at lower temperatures than the corresponding potassium hydrofluorides.

The catalyst may be employed in the solid state, but this is not essential. The hydrocarbon reactants, in a liquid or gaseous condition or in a mixed liquid and gaseous condition, may be passed through a granular mass of the catalyst which is maintained in suitable reactors. The use of a fixed bed of granular material is not essential, however, as the catalyst may be moved, intermittently or continuously, through the reaction zone as the result of continuous or intermittent removal of the catalyst from the bottom of the reactor and continuous replenishment with fresh catalyst at the top of the reactor. In another method of contacting the catalyst and reactants the catalyst is suspended as a powder in the stream of reagents and passed through the reaction zone with the reactants. In another method of operation, powdered catalyst is maintained'as a fluidized, or semi-fluid, mass in the reaction zone by the passage of vaporized reactants upwardly through the reactor. Continuous addition and withdrawal of catalyst is eflected by the suspension 01' catalyst in the stream of reactants and by direct addition and withdrawal by means independent of the stream of reactants. In all operations involving the use of the catalyst in a non-static condition substantially continuous operation is maintained.

Operations in which the catalyst is employed in the molten condition also can be carried out with continuous or intermittent contact of the catalyst and reactants which may be in the liquid or vapor phase or both. For example, liquefied potassium trihydrofiuoride may be intimately mixed with liquid reactants to form an emulsion. A body of such emulsion may be maintained continuously by continuous with drawal of a portion thereof and continuous additions thereto of fresh and recycled reactants and fresh or recycled catalyst.

When the catalyst becomes deactivated, as by the accumulation of carbonaceous deposits thereon or by contamination of a liquefied catalyst by the accumulation therein of hydrocarbonfiuoride complexes, the catalyst may be treated to recover, in part at least, the hydrogen fluoride component. This is done by heating the deactivated catalyst, in the reactor or if withdrawn therefrom, to drive off all or part of the hydrogen fluoride content thereof, which is then reemployed in making further supplies of hydrofluoride catalyst. The metallic fluoride can also be regenerated in such a way as to be suitable for use in preparing additional hydrofluoride addition compounds.

Of the various hydrofluorides mentioned above, those of sodium, potassium and ammonium are preferred, but ammonium hydrofluoride is particularly useful because of its relatively high catalytic activity and because it can be regenerated readily at low temperatures. Its use, however, is limited to reagents at temperatures low enough to avoid decomposition of the ammonium hydrofluoride.

The reaction conditions of temperature, pressure and space velocity, or time of contact, depend upon the nature of the reaction, the reactants, and the character of the desired product.

In polymerization reactions the application of pressure is desirable, and relatively high temperatures are required. For example, in the polymerization of propylene and butylenes, temperatures in the range of 200 F. to 400 F. may be used, with a pressure of 200 pounds per square inch or higher.

In alkylation reactions the application of pressure is less essential since the principal need for pressure is to prevent volatilization of hydrogen fiuoride. In the alkylation of isoparaflin hydrocarbons with olefin hydrocarbons, temperatures in the range of 32 F. to 200 F. may be employed. The alkylation of aromatic hydrocarbons may be effected at lower temperatures, within the range of 32 F. to 150 F.

Isomerization of paraffin hydrocarbons, such actants and recoveredtherefrom, for recirculation, at the exit of the reactor. The use of boron fluoride requires the application of substantial pressure on a reaction zone to insure good contact of the boron fluoride with the hydrofluoride catalyst and the hydrocarbon reactants. For

this purpose puressures of 200 pounds to 500 pounds per square inch are desirable.

The isomerization of olefin hydrocarbons and poly-alkylated naphthenes and aromatics does not require the use of boron fluoride so that these reactions may be conducted under somewhat lower pressure. For the isomerization of olefin hydrocarbons a temperature of F. to 300 F. may be employed while the isomerization of polyalkylated cyclic hydrocarbons may be efiected at a somewhat lower temperature within the range of 100 F. to 200 F.

The space velocity of the reactants in the reaction zone, or the time of residence of the reactants therein, naturally should be long enough to achieve the desired conversion reactions to the maximum extent which is consistent with reasonable suppression of undesired side, or secondary, reactions. The determination of this factor depends upon numerous conditions such as the temperature and pressure employed. the activity of the catalyst, the character of the catalyst, the character of the reaction, the concentration of the reactants in the reaction mixture, etc. In general, condensation reactions proceed much more quickly than do isomerization reactions. For example, the alkylation of benzene with propylene, in accordance with this invention, proceeds at a high rate at room temperature. On the other hand, the isomerization reactions ordinarily require a substantially longer time of contact of the reactants with the catalyst.

In alkylation reactions it is desirable to maintain a fairly high ratio of the hydrocarbons to be alkylated to the olefin hydrocarbon employed for alkylation purposes. This is desirable to promote the alkylation reaction and minimize the occurrence of side reactions, such as direct polymerization of the olefin reactants, hydrofluorina tion, etc.

I claim:

. 1. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization condi tions of temperature, pressure and space velocity in the presence of a catalytic material comprising a compound of hydrogen fluoride and a fluoride selected from the group consisting of the fluorides of the alkali metals, the alkaline earth metals and ammonium as the principal catalytically active component.

2. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions oftemperature, pressure and space velocity in the presence of a catalytic material comprising a double fluoride of hydrogen fluoride and a fluoride selected from the group consisting of the alkali metal fluorides, the alkaline earth metal fluorides and ammonium fluoride as the principal catalytically active component.

3. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising a double fluoride of hydrogen and an alkali metal as the principal catalytically active component.

4. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an iso- 8 merizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising a double fluoride of hydrogen and ammonium as the principal catalytically active component.

5. A method for oatalytically isomerizing a hydrocarbonwhich comprises'subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising an acid metal fluoride selected from the group consisting of the mono and poly; hydrofluorides of the alkali metals, the alkaline earth metals and ammonium as the principal catalytically active component.

6.A method for catalytically isomerizihg a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising an alkali metal hydrofluoride as the principal catalytically active component.

7. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising sodium hyd'rofluoride as the principal catalytically active component.

8. A method for catalytically lsomerizin'g a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic, material comprising potassium hydrofluoride as the principal catalytically active component.

9. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an iso merizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising ammonium hydrofluoride as the principal cataiytioally active component.

10. A method ror catalytically .isomerizing a hydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising a poly-hydrofluoride of an alkali metal as the principal catalytically active component.

compound of hydrogen fluoride and a fluoride selected from the group consisting of the fluorides of the alkali metals, the alkaline earth metals and ammonium as the principal catalytically active component.

13. A method for catalytically isomerizing a hydrocarbon which comprises subjecting a normal paraflin hydrocarbon to isomerization conditions of temperature and pressure in the presence of a catalytic material comprising a double fluoride of hydrogen and an alkali metal as the principal catalytically active component.

14. A method for catalytically isomerlzing a hydrocarbon which comprises subjecting a polyalkylated cyclic hydrocarbon to isomerization conditions of temperature, pressure and space velocity in (the presence of a catalytic material comprising a compound of hydrogen fluoride and a fluoride selected from the group consisting of the fluorides of the alkali metals, the alkaline earth metals and ammonium as the principal catalytically active component.

15. A method for catalytically isomerizing a hydrocarbon which comprises contacting a polyalkylated naphthene with a catalytic material comprising a compound of hydrogen fluoride and a fluoride selected from the group consisting of the fluorides of the alkali metals, the alkaline earth metals and ammonium as the principal catalytically active component.

16. A method for catalytically isomerizing a hydrocarbon which comprises contacting a polyalkylated aromatic with a catalytic material comprising a compound of hydrogen fluoride and a fluoride selected from the group consisting of the fluorides of the alkali metals, the alkaline earth metals and ammonium as the principal catalytically active component.

17. A method for catalytically isomerizing a hydrocarbon which comprises contacting a normal paramn with a catalytic material comprising. a compound of hydrogen fluoride and a fluoride selected from the group consisting of the fluorides of the alkali metals, the alkaline earth metals 11. A method for catalytically isomerizlng ahydrocarbon which comprises subjecting an isomerizable hydrocarbon to isomerization conditions of temperature, pressure andspace velocity in the presence of a catalytic material comprising a poly-hydrofluoride 01' ammonium as the principal catalyticaliy active component.

12. A method for catalytically isomerizing a hydrocarbon which comprises subjecting an allphatic hydrocarbon to isomerization conditions of temperature, pressure and space velocity in the presence of a catalytic material comprising a and ammonium as the principal cataiytically active component and promoted with boron fluoride.

HERBERT J. PAssmo.

REFERENCES crran The following references are of record in the file of this patent:

UNITED STATES PATENTS 

